Proposed work includes (1) the comparison of GFA protein, the subunit of glio-specific filaments with other classes of 100 A filaments: desmin, the muscle-type filament protein, and vimentin, the mesenchymal-type filament protein; (2) the use of 100 A filament proteins as molecular markers for investigations of astroglia during development, in vitro and in experimental pathological conditions leading to fibrous gliosis.